Resolve "Store aliases in global taggable"

Release notes

• aliases are now copied to a globally available TQTaggable object accessible via shared_ptr<TQTaggable> aliases = TQTaggable::getGlobalTaggable("aliases");
• introduced environment variable CAF_PRELOAD_LIBRARIES: names of libraries (e.g. libCAFlwtnn) listed (comma, semicolon or colon separated) in this variable will be loaded as the QFramework python module is loaded
• fixed missing import that would lead to an error at the very end of an analysis run (after writing the SampleFolder)

Details

Closes #254 (closed)